Conventionally, automotive vehicles have a fresh air inlet at the cowling located between the hood and the windshield of the vehicle. The cowling is provided with a screen to keep debris out of the fresh air intake inlet, which is typically located along the side of the windshield on the passenger side of the vehicle. Conventional design of the fresh air inlet places a rain-hat on the inlet opening to restrict the flow of moisture, such as rainwater, into the inlet opening. The conventional rain-hat is simply formed with an upright wall that raises the inlet opening above the level of the channel along the cowling beneath the leaf screen. The raised inlet opening formed by the rain-hat allows for air to flow into the opening, while rainwater flows along the channel around the rain-hat for discharge externally of the vehicle without flowing into the air inlet opening.
The heating, ventilation and air conditioning system (HVAC system) for an automotive vehicle is subjected to a pressure loss due to the aerodynamic choking of the cowl fresh air flow as the intake air separates and creates a recirculation zone due to changing direction of movement while passing over the edge of the rain-hat structure. The increased pressure loss results in a corresponding increase in system noise and causes an uneven loading of the HVAC scroll blower motor wheel. The increased pressure loss also causes more power to be utilized by the HVAC system to overcome the increased HVAC system pressure drop, resulting in electrical charge and fuel economy issues for the vehicle. Filters and other obstruction structure can also be used to separate water from the air intake, but such devices also result in an increased HVAC pressure drop.
Another approach to resolving the increased pressure drop at the fresh air intake opening is to form the rain-hat structure to be larger than the actual opening into the HVAC system. While the flow separation resulting from the inlet of air over the raised rain-hat vertical surface still exists in this enlarged rain-hat structure, the flow separation has a reduced effect on the inflow of fresh air into the inlet opening for the HVAC system beneath the rain-hat; however, some increased pressure loss remains, requiring additional power to operate the HVAC system.
An example of a rain-hat can be found in U.S. Reissue Pat. No. RE38,157, issued to Dean Schneider on Jun. 24, 2003. In Schneider, the rain-hat has first and second supports perpendicular to each other. The draw of the rain-hat is generally parallel to the direction of the airflow. The Schneider rain-hat has a rain dam knife-edge with tapered exterior side edges to improve airflow and reduce air friction U.S. Pat. No. 6,033,300 granted to Dean Schneider on Mar. 7, 2000, discloses a similar rain-hat similar to that of the Schneider patent for use in conjunction with an air intake opening.
U.S. Pat. No. 5,145,457, issued to Yasushi Tanigaito on Sep. 8, 1992, discloses a conventional rain-hat configuration in which the vertical rectangular walls serve as a water stopper to prevent the entry of free water into the air intake. U.S. Patent Application Publication Document No. 2004/0185767 of Dean Schneider, dated Sep. 23, 2004, teaches an example of a filter housing that prevents the entrance of unwanted materials, such as debris and water, into the vehicle air intake. U.S. Patent Application Publication Document No. 2005/0003752 of Keith Lewis, et al, dated Jan. 6, 2005, teach a shield and a deflector for preventing the inflow of debris and water into the HVAC system of an automobile. U.S. Patent Application Publication Document Nos. 2005/0059338 and 2005/0095974 of Lim Wijaya, dated Mar. 17, 2005, and May 5, 2005, respectively, provide a fresh air intake for a rear window of a vehicle.
Accordingly, it would be desirable to provide a rain-hat configuration that will reduce power requirement for the heating, ventilation and air conditioning system for an automotive vehicle by reducing the pressure drop associated with the passage of air over the upright wall of the rain-hat structure.